Implement query & depth restrictions on the GQL interface

[Voxelot]

Overview

Currently, GraphQL queries are unlimited in depth and complexity. It is possible to request all blocks with all transactions and receipts in one query causing OOM on the fuel-core node(plus it consumes a lot of execution).

Solution

We need to implement limits on the complexity and depth of graphql queries to protect the APIs from DOS attacks. This will need to be done carefully, ensuring that the SDK isn't rendered unusable by excessive limits.

Implementation details

https://async-graphql.github.io/async-graphql/en/depth_and_complexity.html